In recent years soft gelatin or soft elastic gelatin capsules have become a popular dosage form for the oral delivery of therapeutic agents, especially over-the-counter pharmaceuticals. These capsules are typically filled with a liquid containing the active ingredient. Because of their soft, elastic character, some patients view these capsules as easier to swallow than conventional tablets or hard gelatin capsules. Since the dosage form is generally swallowed, it is not necessary to flavor or otherwise mask the often unpleasant taste of the pharmaceutical. Soft gelatin capsules are also preferred to bulk liquids because they are easier to transport and they avoid the need for the patient to measure a prescribed amount of the liquid before dosing.
The fill material used in a soft gelatin capsule generally contains a pharmaceutical dissolved or dispersed in a carrier that is compatible with the capsule wall. In addition to liquids, U.S. Pat. No. 4,935,243 to L. Borkan et al. suggests that the fill material may take the form of a semi-solid, solid, or gel. Conventional tablets or pellets containing an active ingredient are examples of solid fill materials that may be encapsulated within a soft gelatin capsule.
Semi-solid (dispersion) fill material are discussed in U.S. Pat. No. 4,486,412 to D. Shah et al. A fill material containing an orally-administered antacid salt that is dispersed in a water-free, liquid carrier containing a major proportion of one or more polyalkylene glycols and a minor proportion of a C.sub.2 -C.sub.5 polyol, such as propylene glycol or glycerin. The carrier forms a stable dispersion of the antacid salt and coats the antacid particles, thereby rendering them nonreactive with the soft gelatin capsule wall. The dispersion may also contain a polysiloxane flatulence-relieving agent, such as simethicone, as an optional ingredients. Such optional ingredients comprise about 0-5% by weight of the total dispersion.
U.S. Pat. No. 4,708,834 to Cohen et al. suggests a controlled release pharmaceutical dosage form comprising a soft gelatin capsule that encloses a watersoluble or dispersible gelled polymer matrix. The fill material comprises an aqueous solution or dispersion of a polysaccharide gum, the pharmaceutical active and, optionally, an alcohol. The liquid fill is introduced into a soft gelatin capsule that contains a cationic gelling agent, which gels the liquid fill after it has been incorporated into the capsule shell. The alcohol used in the fill includes liquid polyethylene glycols, lower alkanols, C.sub.2 -C.sub.4 polyols and mixtures thereof.
U.S. Pat. No. 5,071,643 to M. Yu et al. also discusses the use of polyethylene glycols (PEG) as a fill material in soft gelatin dosage forms. PEGs having an average molecular weight between 400-600 are preferred for liquid fills, between 800-10,000 for semi-solid fills and between 10,000-100,000 for solid fills.
Remington's Pharmaceutical Sciences, 18th ed, Chapter 83, pp. 1539-40 (1990), reports that gelling agents used to make gels for pharmaceutical and cosmetic products, include sodium alginate and triethanolamine.
PCT Publication No. WO 91/07950 describes a soft or two-piece hard gelatin capsule shell containing benzodiazepine dissolved or suspended in a gel. The gel contains by weight at least 63% of polyethylene glycol 600, at least 4% of polyethylene glycol 4000 or 6000, and at least 21% of polyethylene glycol 600-4000. This gel fill cannot be expelled with a syringe at ambient temperature and therefore avoids the reported abuse of liquid filled capsules by intravenous drug abusers.
Antiflatulents are typically incorporated into compressible tablets by mixing the oily-like substances, such as simethicone, with standard tableting excipients prior to tableting. U.S. Pat. No. 5,073,384 to Valentine et al. describes a composition suitable for tableting comprising simethicone and a water soluble, maltodextrin agglomerate. The resulting combinate is reported to be free flowing and possess defoaming activity.
Hungarian Patent No. 203,477, published Jan. 28, 1991, describes an antiflatulent, solid dispersion containing poly(dimethylsiloxane) as a dispersed phase in a water soluble carrier. The dispersion also contains a lattice-forming and/or a crosslinking, viscosity-increasing macromolecular auxiliary substance such as polyvinyl chloride, polyacrylic acid, or polyvinylpyrrolidone and/or inorganic solidifying agent, such as tricalcium phosphate, calcium sulfate hemihydrate or calcium hydrogen phosphate. Example 1 reports a solid mass containing 60 g of polyethylene glycol 6000, 15 g of polyvinyl chloride and 25 g of activated dimethicone (simethicone) that can be ground and filled into solid gelatin capsules or made into tablets.
French Patent Application No. 2,624,012, published Jun. 9, 1989, relates to a soft gelatin capsule containing a suspension or solution of chloral hydrate in a high viscosity inert vehicle. Suitable vehicles for use in the capsule include oily solvents of mineral or vegetable oil, such as olive oil, peanut oil, paraffin oil, vaseline oil or mixtures of several oils; a liquid silicone such as dimethicone or simethicone; a glycol polymer such as polyethylene glycol 600, 800 or 1200; and a glycol such as ethylene glycol, propylene glycol or glycerol.
Simethicone has been incorporated in syrup or clear base liquid oral formulations. A. Banga et al. in "Incorporation of Simethicone into Syrup or Clear Base Liquid Orals," Drug Development and Industrial Pharmacy, 15(5), pgs. 691-704 (1989) describes a variety of vehicles for simethicone, but reports the best results were obtained with neutralized CARBOPOL.RTM. (carboxypolymethylene) resins in combination with glycerin and propylene glycol.
A need exists for a semi-solid fill material containing an antiflatulent suitable for use in the production of soft gelatin capsules. The fill material should be sufficiently viscous so as to prevent it from being expelled from the capsule shell with a syringe to minimize the potential for product tampering. The fill material should also not affect the defoaming properties of the antiflatulent.